#ifndef STAN_MATH_REV_SCAL_FUN_DIGAMMA_HPP
#define STAN_MATH_REV_SCAL_FUN_DIGAMMA_HPP

#include <boost/math/special_functions/zeta.hpp>
#include <stan/math/rev/core.hpp>
#include <stan/math/prim/scal/fun/trigamma.hpp>
#include <stan/math/prim/scal/fun/digamma.hpp>

namespace stan {
  namespace math {

    namespace {
      class digamma_vari : public op_v_vari {
      public:
        explicit digamma_vari(vari* avi) :
          op_v_vari(digamma(avi->val_), avi) {
        }
        void chain() {
          avi_->adj_ += adj_ * trigamma(avi_->val_);
        }
      };
    }

    inline var digamma(const var& a) {
      return var(new digamma_vari(a.vi_));
    }

  }
}
#endif
